Multiple Sprites(Animation)

[Primordial Ooze]

So far I have managed to get the duck to face the direction it is flying as opposed to moon walking. Now i want to make it so when the duck is "hit" it is shown as a different sprite. I know i need to add a new sprite as the Atari 2600 doesn't have a register for flipping a sprite vertically, but need help in coding the flipping of the different sprites. Any assistance would be greatly appreciated.

 

Sincerely,

 

Primordial Ooze

[Omegamatrix]

The simplest way is to just have some extra graphics in the rom for the duck being hit. You could use a pointer in your rom to switch between the graphics. LDA indirect Y addressing is probably the easiest for you to use. You need 2 bytes of ram for that.

 

 

I.e.

duckGfx ds 2

 

 

 

To make a pointer for "FlyingDuck":

 

LDA #<FlyingDuck

STA duckGfx

LDA #>FlyingDuck

STA duckGfx+1

 

Follow a similar procedure for "DyingDuck".

 

When drawing the address mode for indirect Y is like:

 

LDA (duckGfx),Y

STA GRP0

[Omegamatrix]

Forgot to say, but if you're doing multiple frames of animation, then you could use another ram location (probably a few bits is good) for an animation index. Then you simply load your pointers from a table. I would give an example but I'm on my iPad and typing takes a while.